These circles should be local (state level), with an open invition to all in the surrounding geographic area to join conversations and attend the meets. I think this is basically happening, though I don't know that it is well explained and communicated on the circles.
The potential issue with a larger geographical area circle, such as a SE circle, would be administering the logics of meets. Since meets would not happen as often, people would spend a lot of time trying to coordinate agreeable dates to get a high turnout, trying to figure out how to get equipment around, trying to identify a large place to meet, etc. Now there is nothing wrong with this and, it even makes sense once in a while but, it becomes much more of a once, or twice a year "Stereophile" show than a group of hobbyist followshipping, being exposed to more equipment and set-ups, drinking, and talking audiotrash all the while evolving in their hobby.